The present invention relates to plants and apparatus for the electroslag melting of hollow metal ingots, e.g. those similar in geometry to power fitting casings having a longitudinal space in communication with holes in connecting pipes arranged transversely to the longitudinal axis.
The present invention is aimed at providing maximum geometric similarity of an ingot and a finished article which feature making possible a decrease in production costs of shaped articles.
A method for the manufacture of hollow metal ingots by electroslag melting in a cooled outfit (means) is presently known, and which comprises a base plate mounting, a means (a mould) for shaping an external side surface of the ingot with a means (a mandrel) disposed coaxially therewith, and adapted for shaping an internal side surface of the ingot. A mandrel is introduced into an outfit melting space from either above or below.
The mandrel in adapted for introduction into the melting space from above, and is fitted with elements through which it rests on the upper end of the means (mould) for shaping the external surface of the ingot.
The above elements, disposed transversely to the longitudinal axis of the outfit, interfere with the introduction of the hollow consumable electrode into the melting space.
In this connection the hollow metal ingots may only be melted by using consumable electrodes with a solid and comparatively small cross-section so as to enable their introduction into the space between the mould and the mandrel with a clearance.
The hollow consumable electrodes are utilized in plants wherein the mandrel is introduced from below through an opening in the base plate. However, the above plants are not suitable for melting ingots which would ensure a maximum similarity in geometry to the finished articles, e.g. having conduits in connecting pipes.
The melting of hollow metal ingots with openings on their side surface would necessitate reducing the scope of their machining.
The prior art inventors believe that openings on the side surfaces of such ingots can be utilized coupled with the aid of mandrels introduced into the outfit melting space through the holes in the wall of the means for shaping the external side surface of the ingot being melted. However, the side mandrels representing the outfit elements would be disposed transversely to the direction of motion of the consumable electrode in the course of fusing thereof, and thereby hampering the introduction of the hollow consumable electrode into the melting space.
It is due to these problems that at present the casings for the fittings employed in nuclear power engineering are welded from separate stampings or forgings. All this results in a considerable increase in the cost of articles being produced. Moreover, the metal of such articles does not always features adequate strength and homogeneity.
Due to a growing demand for shaped ingots for articles utilized in different branches of industry, a need has arisen to eliminate the above difficulties, and to solve electroslag melting problems involving high-quality metal ingots, and thus ensuring maximum similarity in geometry to the finished articles, e.g. to the power fitting casings with openings in their side surface (in connecting pipes).
The known plants for electroslag melting of hollow metal ingots are not adapted for melting shaped ingots with openings on their side surface.